WO2024009615A1

WO2024009615A1 - Magnesium titanium multiple oxide which is suitable as inorganic filler in resin sealing material for semiconductors, and method for producing same

Info

Publication number: WO2024009615A1
Application number: PCT/JP2023/018192
Authority: WO
Inventors: 智子吉見; 俊之古賀; 有加世堂; 貴康田中
Original assignee: チタン工業株式会社
Priority date: 2022-07-08
Filing date: 2023-05-16
Publication date: 2024-01-11
Also published as: TW202408940A; JP2024008656A

Abstract

The present invention provides a magnesium titanium multiple oxide which has an average primary particle diameter of 300 nm to 5,000 nm as determined by the observation with a transmission electronic microscope, wherein a peak of titanium dioxide is not observed by X-ray diffractometry. With respect to this magnesium titanium multiple oxide, if the powder thereof is immersed in water at a concentration of 100 g/L and is subsequently held at 95°C for 20 h, the amount of sodium and the amount of chlorine dissolved in water are respectively 100 mg or less and 50 mg or less per 1.0 kg of the powder. This powder is suitable as an inorganic filler in a resin sealing material for semiconductors. This powder is produced by: subjecting a titanium source and a magnesium source to wet mixing; adding an alkali to the mixture so that the pH thereof is 9.5 to 13.0; subjecting the mixture to solid-liquid separation and washing with water until the electrical conductivity of the liquid portion falls to 300 µS/cm or less; firing the resulting and subjecting the fired product to acid pickling so that the pH thereof after acid pickling is within the range of 4.0 to 7.0; subjecting the fired product to solid-liquid separation and washing with water until the electrical conductivity of the liquid portion falls to 100 µS/cm or less; and drying the resulting product.

Description

Magnesium titanium double oxide suitable as an inorganic filler in resin encapsulant for semiconductors and method for producing the same

The present invention relates to a magnesium titanium double oxide powder and a method for producing the same. More specifically, the present invention relates to a magnesium titanium double oxide powder suitable as an inorganic filler in resin encapsulants for semiconductors, and a method for producing the same.

Magnesium titanium double oxide powder can be used as a filler in semiconductor encapsulating materials or as a raw material for ceramic capacitors by taking advantage of its dielectric properties, and as an ultraviolet wavelength converting agent for cosmetics because of its low impact on health. It is used for various purposes such as.

Among these, semiconductor encapsulants protect semiconductor elements from mechanical external forces such as shock and pressure, and from external environments such as humidity, heat, and ultraviolet rays.They also protect semiconductor devices from external environments such as humidity, heat, and ultraviolet rays. It also plays such a role. A semiconductor encapsulant is basically composed of a resin component as a main component and a filler dispersed inside the resin component.

Inorganic particles are generally used as fillers in resin encapsulants for semiconductors. JP-A No. 2002-265797 (Patent Document 1) discloses that a resin composition exhibiting a high dielectric constant can be obtained by employing a titanate such as barium titanate as a filler in a resin composition for sealing. It is proposed that In addition to titanates such as barium titanate with a high dielectric constant listed in Patent Document 1, magnesium titanium double oxide is a material with a low dielectric constant among titanates, so it is a material with a high dielectric constant. It is useful when adjusting the dielectric constant of a resin encapsulant for semiconductors to a desired value. Japanese Unexamined Patent Application Publication No. 2001-72418 (Patent Document 2) proposes a method of firing in an atmosphere containing chlorine as a method for producing magnesium titanate with a low dielectric constant used in the field of electronic materials.

On the other hand, epoxy resins are widely used as resin components due to their excellent strength, chemical stability, and the fact that they do not produce by-products during curing. If impurities that are easily ionized, such as sodium or chlorine, are present in the epoxy resin, the electrodes may corrode. This phenomenon is a major challenge in this field because it can lead to wire breaks and unexpected insulation in semiconductors, greatly reducing product reliability. In JP-A No. 2009-144107 (Patent Document 3), impurities in the epoxy resin are reduced. However, on the other hand, it has been found that even if the epoxy resin contains only a small amount of impurities, if the above-mentioned impurities are contained in the inorganic filler, the electrode may still be corroded. Although the exact mechanism is not well understood, it is thought that impurities in the inorganic filler are eluted into the moisture in the epoxy resin, generating ions, which move inside the epoxy resin and reach the electrodes, causing corrosion. It will be done. Although ion trapping agents may be used as a countermeasure, it is not desirable to add substances that are unrelated to the original function of the sealing material. Furthermore, since the ion-trapping agent itself is one of the impurities, considering the risk of leakage to the outside, it is desirable to solve this problem without using the ion-trapping agent. That is, it is desirable to use an inorganic filler in a resin encapsulant for semiconductors that has a small elution amount of impurities such as sodium and chlorine. Although Patent Document 1 discusses the dielectric constant of the resin composition, it does not take into consideration countermeasures against corrosion of metals used for semiconductor element electrodes and wiring. Magnesium titanate obtained by the manufacturing method of Patent Document 2 contains a large amount of chlorine because of the manufacturing method. Therefore, it is considered difficult to use the magnesium titanate obtained by the manufacturing method of Patent Document 2 as a filler in a resin encapsulant for semiconductors.

JP 2007-134465A (Patent Document 4) is an invention related to ferrite particles added to a resin composition for semiconductor encapsulation, and it is described that the ferrite particles have a small amount of soluble ions eluted. However, although the dielectric constant of the ferrite particles is not specified, it is assumed that the dielectric constant is very small compared to magnesium titanium double oxide, so it is used for high dielectric constant semiconductor resin encapsulants. It's difficult to do. Furthermore, since the ferrite particles have a very large particle size with an average particle diameter of 10 to 50 μm, it is difficult to achieve a high filling rate and it is difficult to obtain a resin encapsulant for semiconductors with high strength.

Furthermore, in the ferrite particles described in Patent Document 4, forming a surface layer portion mainly composed of SiO ₂ on the particle surface plays an important role in reducing the amount of eluted soluble ions. However, in order to prevent the elution of internal soluble ions, it is considered necessary that the surface layer mainly composed of SiO ₂ has a certain thickness and is further formed over the entire particle. In fact, in FIG. 2 of Patent Document 4, the surface layer portion mainly composed of SiO ₂ has a thickness of about 1500 nm even at a thin portion. The relative dielectric constant of SiO ₂ is as small as 3.8 in the literature, so even if the particles are made of a substance with a high dielectric constant, if the particles are covered with a thick layer mainly composed of SiO ₂ , There is a possibility that the function as a filler of a high dielectric constant semiconductor resin encapsulant may be impaired. In addition, there is a risk that cracks may occur in the surface layer due to impact, and soluble ions may be eluted. Therefore, it is desirable to reduce the amount of impurities eluted without depending on the surface layer.

A common method for obtaining an inorganic double oxide is to mix a plurality of metal salts and sinter the mixture. Magnesium titanium double oxide can also be obtained by dry mixing a titanium source and a magnesium source and firing the mixture (Non-Patent Document 1). However, the magnesium titanium double oxide obtained in this way generally has a small particle size, so when it is used as a filler in resin encapsulant for semiconductors, it has poor dispersibility and voids are generated inside. Cheap.

Regarding magnesium titanium double oxide, it is possible to increase the particle size of the product by using a titanium source or magnesium source with a large particle size, but the resulting magnesium titanium double oxide However, there were problems such as the reaction was not easily completed and the unreacted titanium dioxide was contained, resulting in a lack of stability of properties. For this reason, it has been difficult to use it in the field of resin encapsulants for semiconductors, which requires strict control of properties including dielectric constant.

On the other hand, when obtaining a magnesium titanium double oxide by wet mixing a titanium source and a magnesium source and then calcining the same, the conventional method causes the magnesium component to dissolve into water, making the substance ratio unstable, resulting in a problem with stable physical properties. It lacked sex. Furthermore, since substances present in water remain in the product, it has been difficult to obtain magnesium titanium double oxide with a small content of impurities.

Japanese Patent Application Publication No. 2002-265797 Japanese Patent Application Publication No. 2001-072418 Japanese Patent Application Publication No. 2009-144107 Japanese Patent Application Publication No. 2007-134465

An object of the present invention is to provide a powder made of magnesium titanium double oxide in which the amount of sodium elution and the amount of chlorine elution are reduced. Furthermore, to provide a powder made of magnesium titanium double oxide, which has a particle size in an appropriate range, does not contain titanium dioxide as an unreacted product, and is suitable for use as an inorganic filler in a resin encapsulant for semiconductors. The task is to

The present inventors conducted intensive studies on reducing the amount of sodium eluted and the amount of chlorine eluted in magnesium titanium double oxide, and found that after wet mixing the raw materials, alkali was added to adjust the pH to 9.5 or higher and 13.0 or higher. Made of magnesium titanium double oxide that satisfies the above conditions by adjusting the following, washing with water until the electrical conductivity of the filtrate is below a specified value, firing, treating with acid, and washing again with water. A powder was obtained.

The magnesium titanium double oxide powder of the present invention has a sodium elution amount of 100 mg or less and a chlorine elution amount of 50 mg or less per 1.0 kg of powder measured by the method described below. Further, the particles constituting the powder have an average primary particle diameter of 300 nm or more and 5000 nm or less as measured by a transmission electron microscope, and no titanium dioxide peak is observed in X-ray diffraction measured under the conditions described below. The present invention includes, but is not limited to, the following:
[Aspect 1]
Sodium in the powder that has an average primary particle diameter of 300 nm or more and 5000 nm or less as observed by transmission electron microscopy, and that dissolves into water when the powder is immersed in water at a concentration of 100 g/L and held at 95°C for 20 hours. The amount of chlorine is 100 mg or less per 1.0 kg of powder, the amount of chlorine is 50 mg or less per 1.0 kg of powder,
A magnesium titanium double oxide powder in which no titanium dioxide peak is observed in X-ray diffraction.
[Aspect 2]
The magnesium titanium double oxide powder according to aspect 1, wherein the sodium content per 1.0 kg of powder is 1000 mg or less, and the chlorine content per 1.0 kg of powder is 50 mg or less.
[Aspect 3]
The magnesium titanium double oxide powder according to aspect 1 or 2, wherein the amount of sodium dissolved in water is 85 mmol/mol or less among the sodium contained therein.
[Aspect 4]
The magnesium titanium double oxide powder according to any one of aspects 1 to 3, which has a boiled linseed oil absorption amount of 14 mL/100 g or more and 45 mL/100 g or less.
[Aspect 5]
The magnesium titanium double oxide powder according to any one of aspects 1 to 4, which has a median diameter of 0.5 μm or more and 10.0 μm or less as measured by laser scattering diffraction particle size analysis.
[Aspect 6]
Any of aspects 1 to 5, wherein the crystallite diameter in the (104) plane of MgTiO ₃ that appears in the range of 32.00° or more and 33.50° or less at a diffraction angle 2θ in X-ray diffraction is in the range of 60 nm or more and 130 nm or less. Magnesium titanium double oxide powder described in Crab.
[Aspect 7]
A method for producing a magnesium titanium double oxide powder according to any one of aspects 1 to 6, comprising the following steps A to E.
A: A step of mixing a titanium source and a magnesium source in a wet state, adding an alkali, and adjusting the pH to a range of 9.5 or more and 13.0 or less to obtain a slurry,
B: washing the slurry obtained in step A with water until the electrical conductivity of the liquid part becomes 300 μS/cm or less, and performing solid-liquid separation to obtain a mixture of a titanium source and a magnesium source;
C: a step of firing the mixture obtained in step B and reacting the titanium source and the magnesium source to obtain a fired product;
D: A step of washing the baked product obtained in step C with an acid and adjusting the pH to a range of 4.0 to 7.0 to obtain a slurry;
E: washing the slurry obtained in step D with water until the electrical conductivity of the liquid part becomes 100 μS/cm or less, and performing solid-liquid separation to obtain a solid content;
F: Step of drying the solid content obtained in Step E.
[Aspect 8]
The method for producing a magnesium titanium double oxide powder according to aspect 7, wherein the alkali added in the step A is a sodium compound and/or a potassium compound.
[Aspect 9]
The method for producing a magnesium titanium double oxide powder according to aspect 7 or 8, further comprising the step of applying an inorganic or organic coating layer to at least a part of the surface of the particles constituting the powder.
[Aspect 10]
The magnesium titanium double oxide powder according to any one of aspects 1 to 6, which has an inorganic or organic coating layer on the powder surface.
[Aspect 11]
An inorganic filler used in a resin encapsulant for semiconductors, which contains the magnesium titanium double oxide powder according to any one of aspects 1 to 6.

When the magnesium titanium double oxide powder of the present invention is used as a filler in resin encapsulants for semiconductors, it prevents corrosion of metals used in electrodes and wiring because the amount of sodium and chlorine eluted is small. Is possible. Moreover, since the particle size is appropriate, it is excellent in usability, and furthermore, since it does not contain unreacted substances (titanium dioxide), the properties are stable. Magnesium titanium double oxide has a low dielectric constant among titanates, so by using the magnesium titanium double oxide powder of the present invention, the dielectric constant of a resin encapsulant for semiconductors with a high dielectric constant can be finely adjusted. becomes possible.

One of the effects of the present invention is that even if there is some variation in the sodium content of the powder itself, the amount of sodium eluted per 1.0 kg of powder is 100 mg or less. The magnesium titanium double oxide powder of the present invention and its manufacturing method are suitable even in cases where it is desired to reduce the amount of sodium eluted but it is difficult to reduce the sodium content in the powder due to the manufacturing process or product characteristics. .

Furthermore, one of the effects of the magnesium titanium double oxide powder of the present invention is that the amount of sodium and chlorine eluted is small even if the particles forming the powder do not have a coating layer on the surface. This has the advantage that the amount of sodium and chlorine eluted will not increase rapidly even if part of the particle surface is damaged by physical factors such as impact or chemical factors such as organic solvents, acids, and bases. . Further, even when a coating layer is newly formed on the surface of the particles forming the magnesium titanium double oxide powder of the present invention, the above effects are not impaired. As described above, the magnesium titanium double oxide powder of the present invention can be used in a wide range of processes, types of resins, and substances used in combination, and there is a large degree of freedom in design.

3 is a transmission electron micrograph of the magnesium titanium double oxide powder obtained in Example 4. 3 is an X-ray diffraction pattern of the magnesium titanium double oxide powder obtained in Example 3. FIG. 3 is a particle size distribution diagram of magnesium titanium double oxide powder obtained in Example 9.

The magnesium titanium double oxide powder of the present invention and the method for producing the same will be described in detail below based on embodiments.
As used herein, "powder" refers to an aggregate of particles.

In this specification, when it is simply written as "magnesium titanate", it refers to MgTiO ₃ . Moreover, when it is simply written as "titanium dioxide", it refers to _TiO2 .
The magnesium titanium double oxide powder of the present invention is made of magnesium titanate, but may also contain dimagnesium titanate, which is Mg ₂ TiO ₄ , and magnesium dititanate, which is MgTi ₂ O ₅ . The total of magnesium titanate, dimagnesium titanate, and magnesium dititanate preferably accounts for 900 g/kg or more of the mass of the magnesium titanium double oxide powder, more preferably 950 g/kg or more, and 980 g It is more preferable that the amount is at least /kg. The upper limit is not particularly limited, and it is most preferable that no components other than the above-mentioned substances are present, that is, the total of the above-mentioned substances occupies 1000 g/kg.

The magnesium titanium double oxide powder of this embodiment was tested in a hot water extraction test in which the powder was dispersed in water at a concentration of 100 g/L, held at 95°C for 20 hours, and then solid-liquid separated. The amount of sodium eluted per 0 kg is 100 mg or less and the amount of chlorine eluted is 50 mg or less. By controlling the elution amount of sodium and chlorine within the above range, it can be suitably used as a filler in a resin encapsulant for semiconductors. On the other hand, if the amount of sodium elution and/or the amount of chlorine elution is larger than the above range, metals used for semiconductor device electrodes and wiring will corrode, and the object of the present invention cannot be achieved. The lower limit is not particularly limited, and it is most preferable that neither sodium nor chlorine is eluted at all, that is, the amount eluted is 0 mg. Preferably, the amount of sodium eluted per 1.0 kg of magnesium titanium double oxide powder is 50 mg or less and the amount of chlorine eluted is 30 mg or less, more preferably the amount of sodium eluted is 20 mg or less and the amount of chlorine eluted is 10 mg or less, and sodium The elution amount is more preferably 10 mg or less.

The particles constituting the magnesium titanium double oxide powder of this embodiment have an average primary particle diameter of 300 nm or more and 5000 nm or less as observed with a transmission electron microscope. If the average primary particle diameter is 300 nm or more and 5000 nm or less, the specific surface area of the particles will not become too large, so elution of sodium and chlorine will be suppressed, and dispersibility in the resin will improve, creating voids between the particles and the resin. At the same time, it becomes easier to increase the filling rate of the resin, improving usability. The lower limit is preferably 310 nm or more, more preferably 400 nm or more, still more preferably 500 nm or more, and the upper limit is preferably 3000 nm or less, more preferably 2000 nm or less, still more preferably 1500 nm or less, even more preferably 1000 nm or less. A method for evaluating the average primary particle diameter by transmission electron microscopy will be described later.

In the magnesium titanium double oxide powder of this embodiment, no titanium dioxide peak is observed in X-ray diffraction measurement. The fact that a titanium dioxide peak is not observed is evidence that the reaction has been completed during the manufacturing process, and the obtained magnesium titanium double oxide is suitable for use as a filler in semiconductor resin encapsulants. It can be said that it has sufficient purity. The method of X-ray diffraction measurement will be described later. Note that the titanium dioxide peak "not observed" refers to the fact that the titanium dioxide peak cannot be confirmed on the pattern printed by the method described below, but if a threshold value is to be determined, the titanium dioxide peak intensity is This refers to a state in which the peak intensity is less than 2.0% of the peak intensity of the (104) plane of titanium double oxide.

A particularly advantageous feature of the magnesium titanium double oxide powder of this embodiment is that the sodium it contains is difficult to dissolve into water. In the magnesium titanium double oxide powder of this embodiment, only 85 mmol/mol or less of the sodium contained in the powder dissolves in water. Although not completely elucidated, it is thought that the sodium in the magnesium titanium double oxide powder of the present invention is firmly held within the structure of the magnesium titanium double oxide. By employing the manufacturing method of the present invention, which will be described later, it becomes possible to obtain an inorganic filler with a small amount of sodium elution, for example, without significantly changing the raw material composition or raw material blending ratio that has been conventionally used. The upper limit of the proportion of sodium eluted in water out of the sodium contained is more preferably 80 mmol/mol or less, and still more preferably 60 mmol/mol or less. The lower limit is not particularly limited, and is most preferably 0 mmol/mol, at which no elution occurs.

From the viewpoint of suppressing corrosion of metals used in electrodes and wiring, it is preferable that the magnesium titanium double oxide powder of the present embodiment also has a small elution amount of impurities other than sodium and chlorine. In particular, it is preferable that the elution amount of sulfur and ammonia is small. Specifically, in the hot water extraction test described above, it is preferable that the elution amount of sulfur is 10 mg or less per 1.0 kg of powder in terms of sulfur tetroxide ion, and for ammonia, the elution amount of ammonium ions is preferably 10 mg or less per 1.0 kg of powder. The amount is preferably 10 mg or less. The lower limit is not particularly limited, and it is most preferable that neither sulfur nor ammonia be eluted at all, that is, the amount eluted is 0 mg. The evaluation method for sulfur tetroxide ions and ammonium ions eluted into water is not particularly limited, but typically a method based on JIS K0102:2019 using ion chromatography or indophenol blue absorption spectrophotometry is used. can be evaluated based on As for other impurities, it is desirable that the amount eluted is small.

The magnesium titanium double oxide powder of the present embodiment preferably has a small content of sodium and chlorine in view of the objective of the present invention of reducing the amount of sodium and chlorine eluted. If the sodium content is 1000 mg or less and the chlorine content is 50 mg or less per 1.0 kg of magnesium titanium double oxide powder, the elution amount is likely to be within the permissible range. The upper limit of the sodium content is more preferably 900 mg or less per 1.0 kg of the magnesium titanium double oxide powder, and the upper limit of the chlorine content is more preferably 30 mg or less per 1.0 kg of the magnesium titanium double oxide powder. The evaluation method for the content of sodium and chlorine will be described later.

The lower limit of the sodium content is not particularly limited. However, basically, as the content of sodium and chlorine is reduced, the cost required for washing with water and the like increases. From the viewpoint of achieving the two objectives of reducing the elution amount while suppressing the cost, it is difficult to make a general statement, but if the sodium content per 1.0 kg of magnesium titanium double oxide powder is 200 mg or more, the chlorine content is A preferable range is a content of 5 mg or more. Of course, if cost can be ignored, the lower the content of both sodium and chlorine, the better.

The particles constituting the magnesium titanium double oxide powder of this embodiment are magnesium titanate MgTiO ₃ crystals in the (104) plane that appear in the range of 32.00° or more and 35.50° or less in 2θ in X-ray diffraction. It is preferable that the particle diameter is 60 nm or more and 130 nm or less. If the crystallite diameter is within the above range, it can be said that the distortion of the crystal lattice is within an allowable range in view of the purpose of the present invention. The crystallite diameter is more preferably a lower limit of 90 nm or more and an upper limit of 120 nm or less.

The magnesium titanium double oxide powder of this embodiment preferably has a boiled linseed oil absorption amount of 14 mL/100 g or more and 45 mL/100 g or less. When the boiled linseed oil absorption amount is within the above range, the specific surface area of the particles becomes small, thereby suppressing the elution of sodium and chlorine, and further improving the usability when used as a filler. More preferably, the upper limit is 20 mL/100 g or less. Boiled linseed oil absorption is evaluated by a method based on JIS K5101-13-2 described below.

The magnesium titanium double oxide powder of this embodiment preferably has a median diameter of 0.5 μm or more and 10.0 μm or less as determined by laser scattering diffraction. If the median diameter is within the above range, it can be determined that large secondary agglomerated particles are unlikely to occur and the particles can maintain a certain size or more in the fluid. More preferably, the upper limit is 5.0 μm or less, still more preferably 4.0 μm or less. The median diameter is evaluated by a method according to JIS-Z-8825:2013, which will be described later.

The particle size distribution and particle shape of the particles constituting the magnesium titanium double oxide powder of the present invention are not particularly limited. However, considering the purpose of the present invention, it can be said that it is desirable that the particle size distribution is small and the particle surface has few irregularities.

The specific surface area of the particles constituting the magnesium titanium double oxide powder of the present invention is not particularly limited. As a guideline, if the specific surface area is 0.5 m ² /g or more and 6.0 m ² /g or less, the elution of sodium and chlorine will be suppressed, and the dispersibility in the resin will improve, so that the distance between the resin and the resin will be reduced. This is preferable because voids are less likely to occur in the resin and at the same time it becomes easier to increase the filling rate of the resin. More preferably, the upper limit is 5.0 m ² /g or less. The specific surface area can be evaluated by the BET method. It can be said that one of the excellent features of the present invention is that it is possible to obtain a magnesium titanium double oxide powder in which the amount of sodium and chlorine eluted is small within such a specific surface area range.

(Production method)
The method for producing the magnesium titanium double oxide powder of the present invention will be described below.
The magnesium titanium double oxide powder of this embodiment can be manufactured by a manufacturing method including the following steps A to F.
A: A step of mixing a titanium source and a magnesium source in a wet state, adding an alkali, and adjusting the pH to a range of 9.5 or more and 13.0 or less to obtain a slurry,
B: washing the slurry obtained in step A with water until the electrical conductivity of the liquid part becomes 300 μS/cm or less, and performing solid-liquid separation to obtain a mixture of a titanium source and a magnesium source;
C: a step of firing the mixture obtained in step B and reacting the titanium source and the magnesium source to obtain a fired product;
D: A step of washing the baked product obtained in step C with an acid and adjusting the pH to a range of 4.0 to 7.0 to obtain a slurry;
E: washing the slurry obtained in step D with water until the electrical conductivity of the liquid part becomes 100 μS/cm or less, and performing solid-liquid separation to obtain a solid content;
F: Step of drying the solid content obtained in Step E.

One of the features of the method for producing magnesium titanium double oxide powder of the present invention is that the titanium source and the magnesium source are mainly wet mixed in a pH range of 9.5 to 13.0, so that the electrical conductivity of the liquid part is maintained at a predetermined level. After washing with water until the value becomes below the value of The pH during wet mixing in step A is referred to as "first adjusted pH."

Examples of titanium sources include anatase-type titanium dioxide, rutile-type titanium dioxide, titanium dioxide having two phases of anatase-type and rutile-type, and metatitanic acid. Although not particularly limited, a typical example is metatitanic acid, which is relatively easy to complete the reaction with the magnesium source from the viewpoint of diffusion rate. Metatitanic acid is also advantageous in obtaining a magnesium titanium double oxide having a large particle size. It is generally desirable that the titanium source has a low content of substances that can remain as impurities in the product. The titanium source may be calcined before being mixed with the magnesium source.

The magnesium source is not particularly limited, but typically includes magnesium salts such as magnesium hydroxide, magnesium carbonate, magnesium sulfate, magnesium oxalate, magnesium nitrate, and magnesium chloride, and magnesium oxide. The magnesium source is generally preferred to be magnesium hydroxide or magnesium carbonate, which contains a large amount of magnesium, easily reacts with the titanium source, and does not contain impurities such as chlorine or sulfur that cause corrosion of the product. The magnesium source may be pre-milled before mixing with the titanium source.

When producing the magnesium titanium double oxide powder of the present invention, it is preferable to mix the raw materials wetly. By mixing the raw materials in a wet manner, the magnesium source and the titanium source are mixed more uniformly in a macroscopic area, and the distance between the magnesium source and the titanium source is further reduced by evaporation of water. As a result, it becomes possible to obtain particles having a larger average primary particle diameter. The magnesium titanium double oxide powder thus obtained has a low probability of having unreacted substances remaining.

The magnesium source and titanium source can be wet mixed by any method. During mixing, equipment such as a sieve, a mixer, a mill, etc. can be used as necessary. Generally, when it is necessary to grind a titanium source or a magnesium source, it is efficient to perform grinding and mixing in the same process. There are no particular limitations on the procedure as long as the finally ground titanium source and magnesium source are mixed. In this case, it is preferable to use materials with as small a particle size as possible for the magnesium source and the titanium source. Even if the material ratio of titanium and magnesium is appropriate, if the titanium source and magnesium source are not mixed uniformly, the desired magnesium titanium double oxide powder may not be obtained, so mix them uniformly. This is desirable.

When mixing the titanium source and the magnesium source, in order to complete the reaction, the amount of magnesium is preferably greater than 1.0 mol when the amount of titanium is 1.0 mol. Although not fully understood, it is believed that an excess of magnesium relative to titanium during wet mixing facilitates contact of the individual titanium sources with the magnesium source. The amount of magnesium per 1.0 mol of titanium is more preferably 1.1 mol or more, and even more preferably 1.2 mol or more. Although the upper limit of the amount of magnesium with respect to 1.0 mol of titanium is not particularly limited, if the amount of magnesium is too large, the cost for obtaining the magnesium titanium double oxide powder increases. Although it cannot be generalized, it is preferable that the amount of magnesium is 3.0 mol or less when the amount of titanium is 1.0 mol, since it can be manufactured at low cost, and more preferably 2.0 mol or less. , more preferably 1.6 mol or less.

In the raw material mixing step A, by adding an alkali and adjusting the first adjusted pH to a range of 9.5 or more and 13.0 or less, excessive dissolution of magnesium can be prevented and the substance amount ratio can be stabilized. When the first adjusted pH is within the above range, the substance ratio of magnesium and titanium is maintained within an appropriate range, and a magnesium titanium double oxide powder containing no unreacted substances can be obtained. Furthermore, it is advantageous to add an alkali to obtain a magnesium titanium double oxide composed of particles having a large average primary particle size. The lower limit of the first adjusted pH is preferably 9.7 or higher, more preferably 9.9 or higher, even more preferably 10.0 or higher, and even more preferably 11.0 or higher. The upper limit is more preferably 12.0 or less.

As the alkali mentioned above, compounds such as sodium, potassium and calcium can be used. Particularly preferred are these hydroxides. Furthermore, in consideration of solubility and usability, compounds containing sodium or potassium are more preferred. Two or more of these compounds may be used in combination. Particularly preferred is sodium hydroxide. It can be said that one of the excellent features of the production method of the present invention is that it is possible to obtain a magnesium titanium double oxide powder with a small amount of sodium eluted even when a compound containing sodium is added.

Another feature of the method for producing magnesium titanium double oxide powder of the present invention is that washing with water (step B) is performed after the raw material mixing step (step A) in order to remove the added alkali. (Water washing in step B will be referred to as "first water washing"). For washing, use ion-exchanged water unless otherwise specified. The method of first washing using a filter press is shown below. When using a filter press, perform both forward and back cleaning. Note that forward cleaning is a cleaning method in which a cleaning liquid is flowed onto the cake from a slurry supply port, and backwashing is a cleaning method in which a cleaning liquid is flowed into the cake from a filter cloth. At least some of the impurities that could not be removed by forward cleaning can be removed by adding backwashing. It is not practical to evaluate the elution amount or content of sodium and chlorine during water washing due to the time required and the capacity of the equipment. Here, the electrical conductivity of the filtrate is thought to be correlated with the amount of impurities such as sodium and chlorine eluted into water, so we used the electrical conductivity of the collected filtrate as an index to determine whether forward cleaning or back cleaning was performed. to determine when to switch and when to finish washing. The first water washing is continued at least until the electrical conductivity of the liquid portion (filtrate) becomes 300 μS/cm or less. The time required for washing with water is not particularly limited, as it varies greatly depending on conditions such as the amount of raw materials, air temperature, and water temperature. Note that the time required to reproduce the first water washing in Examples and Comparative Examples to be described later is 1 hour or more and 24 hours or less, just as a guide. The electrical conductivity of the liquid portion is more preferably 100 μS/cm or less, and even more preferably 20 μS/cm or less. In addition, when adjusting the electrical conductivity of the liquid part to be below a predetermined value, the manufacturing cost increases due to the longer washing time, but it has a particularly negative effect on the properties of the produced magnesium titanium double oxide powder. does not occur.

In the water washing step, in order to efficiently proceed with filtration and solid-liquid separation, a flocculant can be added as necessary for the purpose of, for example, preventing clogging of the filter. The type of flocculant is not particularly limited, and both inorganic flocculants such as aluminum-based and iron-based flocculants and polymer flocculants can be used. Considering the purpose of the present invention, which is to obtain a magnesium titanium double oxide powder with a reduced amount of impurities eluted and a reduced content of unreacted substances, it is preferable to use a polymer flocculant whose components can be easily removed through a process such as calcination. However, it can be said that it is preferable. Among these, any of anionic, cationic, and nonionic polymer flocculants can be used. An inorganic flocculant and a polymer flocculant may be used together, or two or more types of inorganic flocculants or two or more types of polymer flocculants may be used. In general, the selection is made depending on factors such as the scale, the pH and concentration of the slurry, the desired size and viscosity of the flocs, and the properties and price of the flocculant. For example, but not limited to these, anionic polymer flocculants such as polyacrylamide, cationic polymer flocculants such as polyacrylic ester and polymethacrylic acid ester, etc. may be used as necessary. .

In addition to the method using a filter press, methods that can be used for the first washing include a decantation method. In the decantation method, a slurry to which alkali has been added is allowed to stand still in a container, and after confirming that the solid content has settled to the bottom of the container, the supernatant is discarded. Add water again to settle, and repeat this process until all impurities are removed. For the same reason as when using a filter press, it is preferable to use the electrical conductivity of the liquid portion (supernatant liquid) as an index. The structure and size of the container used for washing are not particularly limited, but the weight of the water when filled with water is 3 times or more, more preferably 5 times or more, and still more preferably 10 times or more the weight of the solids. Select a suitable container. Furthermore, since it is difficult to obtain a hard cake using only the decantation method, a water-containing cake can be obtained by applying the slurry to a filter press once the electrical conductivity of the supernatant reaches a standard value. Although the decantation method is more difficult to automate than the filter press method, it requires less water and allows direct confirmation of the properties of the sediment, so it is used when the sample is small or the properties of the product are unknown. It is desirable to do so. Another method using Nutsche can be mentioned. Two or more of these methods may be combined. In any case, for example, the first water washing is continued until the electrical conductivity of the supernatant liquid in the decantation method and the filtrate in the Nutsche method becomes 300 μS/cm or less.

The water-containing cake obtained after the first water washing is subjected to solid-liquid separation.
The mixture of titanium source and magnesium source obtained by solid-liquid separation is then dried. The drying temperature is preferably 70°C or higher and 170°C or lower. Within the above temperature range, the reaction will not proceed in the mixture.

When producing the magnesium titanium double oxide powder of the present invention, it is not necessary to add substances other than the titanium source and the magnesium source, but if necessary, mixing aids, substances that promote or inhibit calcination, and hardness may be added. Adjusting substances may also be added. Specifically, water is added for mixing, Li ₂ O is added as a firing aid, and organic substances such as sugar are added to create fine cavities inside and reduce strength. It will be done. In the present invention, it is necessary to control the types and contents of the components contained in the additives so that the components in the additives do not impair the purpose of the present invention.

By firing the obtained mixture, the titanium source and the magnesium source are reacted (Step C). The firing temperature is preferably 700° C. or higher since it is possible to obtain a magnesium titanium double oxide with high purity. In particular, by firing at a high temperature, the reaction between the magnesium source and the titanium source can proceed more easily. As a result, there is no remaining unreacted titanium source, and it is possible to synthesize highly pure magnesium titanium double oxide powder. Furthermore, by firing at a high temperature, the particle shape has a small specific surface area, so that the elution of impurities from the surface of the magnesium titanium double oxide powder is suppressed. The firing temperature is more preferably 800°C or higher, and even more preferably 900°C or higher. There is no particular upper limit, but if the temperature is too high, the cost for obtaining magnesium titanium double oxide powder will increase, and restrictions on usable equipment and safety will also increase. Generally, as long as the firing temperature does not exceed 1200°C, industrial production can be easily achieved, so it is preferably 1200°C or lower. The firing time is not particularly limited, but is preferably 0.5 h or more, more preferably 0.67 h or more. Generally, it is preferable to remove as much moisture as possible before firing in order to allow the desired reaction to proceed.

The particles constituting the powder obtained by firing have byproducts typified by magnesium oxide on the surface of the particles immediately after firing. In order to dissolve and remove these by-products, it is necessary to wash the powder using an acid (Step D). The cleaning operation itself is no different from cleaning powder using water in general chemical experiments, except for safety and measures to prevent leakage. Although the type and pH of the acid are not particularly limited, hydrochloric acid and the like are preferred as they are inexpensive and do not easily remain on the surface of the magnesium titanium double oxide powder. Washing with acid may be performed multiple times. Further, the powder may be washed with water before washing with acid. Furthermore, for example, washing with acid and washing with water may be repeated alternately, such as washing with acid, washing with water, and washing with acid again. Before moving from washing with acid to washing with water, the pH is adjusted to a range of 4.0 to 7.0 (hereinafter referred to as "second adjusted pH"). When the second adjusted pH is 4.0 or more and 7.0 or less, it is possible to reduce the amount of sodium and chlorine eluted without significantly changing the substance ratio or the amount of product produced. The upper limit of the second adjusted pH is preferably 6.5 or less, more preferably 6.0 or less. The lower limit is preferably 4.5 or more, more preferably 4.7 or more. One of the excellent features of the production method of the present invention is that it is possible to obtain a magnesium titanium double oxide powder with a small amount of chlorine elution even when a chlorine-containing compound such as hydrochloric acid is used during the production process. I can say that.

The third feature of the method for producing magnesium titanium double oxide powder of the present invention is that after completing the above-mentioned washing with acid (step D), washing with water (step E) is further carried out (hereinafter referred to as "second step"). (Wash with water). Normally, a filter press is used, and in the second washing, both forward washing and back washing are carried out in the same way as in the first washing. The remaining amount of impurities is estimated from the electrical conductivity value of the liquid part (filtrate in the case of a filter press), and it is determined whether to switch the washing method or to end the washing. Regarding the second water washing, the washing is continued until the electrical conductivity of the liquid portion becomes 100 μS/cm or less. Although the washing time is not particularly limited, it is generally the same as or shorter than the first washing in many cases. The water-containing cake after the second water washing is also subjected to solid-liquid separation.

The second washing may also be carried out by a method that does not use a filter press, such as a decantation method or a method using a Nutsche. Washing with water may be carried out by appropriately combining these methods. In any case, for example, the second water washing is continued until the electrical conductivity of the supernatant liquid in the decantation method, or of the filtrate in the case of the Nutsche method, becomes 100 μS/cm or less.

The obtained solid content is dried to remove moisture (Step F). The drying temperature is preferably 70°C or higher and 170°C or lower.
The dried product may be pulverized as appropriate. The method of pulverization is not particularly limited. Known methods such as a ball mill, a vibration mill, a jet mill, and an impact crusher can be used without limitation. The method of pulverization is determined by considering the particle size, the proportion of coarse particles in the pulverized product, cost, etc. In addition, operations such as classification may be performed after pulverization. These operations are not restricted in any way.

The obtained magnesium titanium double oxide powder contains aluminum, silicon, A coating layer of an inorganic material such as a hydrous oxide or oxide of metals such as zinc, titanium, zirconium, iron, cerium, and tin may be applied. Metal salts other than those mentioned above may be used as the inorganic coating. Furthermore, an organic coating layer may be applied to at least a portion of the surface of the particles in order to perform surface modification. When forming the coating layer, considering the purpose of the present invention to obtain a resin encapsulant for semiconductors with a high dielectric constant and a small amount of impurity elution, it is necessary to increase the amount of the material used for forming the coating layer. It is preferable that the amount is not too high, and it is further desirable to control the components in the material. It should be noted that the coating layer formed for this purpose will play a role if it has an overlapping layer of about 3 molecules of the substance to be coated, and it is sufficient to have a layer of about 5 molecules overlapped at most. Conceivable. For example, the value obtained by subtracting the average primary particle diameter before coating from the average primary particle diameter after coating, evaluated by the method described below, is preferably 200 nm or less. Moreover, the mass of the coating layer is preferably less than 50 g/kg of the entire particle. Further, in the present invention, it is preferable that the dielectric constant of the powder does not change before and after coating.

Examples of organic coatings include silicone compounds such as dimethylpolysiloxane, hydrogen dimethicone, and polysiloxane, coupling agents such as silane, aluminum, titanium, and zirconium, hydrocarbons, lecithin, amino acids, polyethylene, wax, and metal soaps. For example, processing such as A plurality of these processes may be combined, and there is no particular restriction on the order of the processes. The surface treatment method is not particularly limited, and any commonly used method may be used. For example, dry treatment is performed in a high-speed stirring mixer such as a Henschel mixer, or the conductive powder is dispersed in an organic solvent or water to form a suspension, and an organic substance is added to the solution for coating treatment. There are methods etc. When treating organic substances uniformly on the surface, the latter treatment in a solution is suitable, but in the case of an organic solvent system, distillation operation, pulverization, etc. are required, and in the case of an aqueous system, solid-liquid separation, drying, pulverization, etc. steps are required. Therefore, in terms of ease of production and cost, a method using a high-speed stirring mixer such as a Henschel mixer is preferred. Further, the coating layer can be formed by mixing the material of the coating layer and the powder and then subjecting the mixture to heat treatment. There are no restrictions on which process the surface treatment is carried out, but in general, it is better to carry out cleaning and drying, including washing with acid, to increase the purity to a certain extent, as this will result in a higher coverage rate. This is preferable because the coating layer is difficult to peel off.

(Application)
The magnesium titanium double oxide powder of the present invention can be suitably used as a filler in resin encapsulants for semiconductors mainly composed of epoxy resin compositions, etc., and provides moisture resistance, bending strength, and It can impart excellent properties such as good fluidity. Semiconductor devices encapsulated with such resin compositions have excellent electrical properties, are resistant to metal deterioration, have excellent weather resistance, and have a good balance of properties, making them highly reliable. It is. The composition of the resin component in the semiconductor resin encapsulant is not particularly limited. Further, other fillers and other components such as flame retardants may be used in combination.

The magnesium titanium double oxide powder of the present invention can also be used for purposes other than inorganic fillers in resin encapsulants for semiconductors. For example, the feature of the present invention that the content of unreacted substances and impurities is small is useful for use in the field of electronic materials that requires precise quality control, and specific examples include ceramic capacitors. In particular, the feature that the amount of impurities eluted is small suppresses corrosion and deterioration of surrounding components, making it extremely useful when used in electronic components manufactured by combining various materials, such as displays. Taking advantage of the fact that magnesium titanium double oxide has a lower dielectric constant than titanates, it is also suitable for use as an external additive for toner. Further, the characteristics of the magnesium titanium double oxide powder of the present invention, which have a large particle size and do not contain titanium dioxide, can be said to be advantageous for use in the field of cosmetics, considering the recent increase in health consciousness.

Prior to explaining the examples, the test method used in the present invention will be explained.
[Sodium/chlorine elution amount]
Magnesium titanium double oxide powder is added at a rate of 100g to 1L of water (hereinafter referred to as "ultrapure water") with an electrical resistance of 18.2MΩ cm at 25.0°C, and the whole is made uniform. After dispersing the powder, the mixture was kept in an oven at 95°C for 20 hours to extract sodium, and the powder was removed by centrifugation at 3000 rpm for 30 minutes (this will be referred to as "centrifugation supernatant"). The centrifuged supernatant was measured using an inductively coupled plasma emission spectrometer PS3520UVDD II (hereinafter referred to as "ICP") manufactured by Hitachi High-Tech Science Co., Ltd., to determine the amount of sodium eluted per 1.0 kg of powder.

To determine the chlorine concentration, after measuring a standard sample and creating a calibration curve, the blank and the extracted centrifugation supernatant were measured using an ion chromatograph DIONEX (registered trademark) INTEGRION (registered trademark) manufactured by Thermo Fisher Scientific Co., Ltd. (hereinafter referred to as " The amount of chlorine eluted per 1.0 kg of powder was determined. The lower detection limit of the chlorine content of this device is 0.2 mg of chlorine per 1.0 kg of centrifugal supernatant. From this, if the amount of chlorine is less than 2 mg per 1.0 kg of magnesium titanium double oxide powder, it is below the detection limit.

[Sodium content]
0.25 g of magnesium titanium double oxide powder was heated and dissolved in 20 mL of an acidic solution, and after cooling, ultrapure water was added to dilute the solution 5 times. Further, 20 mL of an acidic solution to which no magnesium titanium double oxide powder was added was diluted five times (this will be referred to as a "blank"). 3 mL of sodium standard solution was added to each diluted solution and measured using ICP. When the amount of sodium in the solution containing the sample is b (mg) and the amount of sodium in the blank is c (mg), the sodium content a (mg/kg) is expressed by the following formula.
a=1000・(b−c)/0.25

[Percentage of eluted sodium]
The value (mmol/mol) obtained by dividing the eluted amount of sodium determined by the above method by the sodium content determined by the above method was taken as the ratio of eluted sodium.

[Chlorine content]
0.05 g of magnesium titanium double oxide powder was placed in a combustion decomposition device AQF-2100H manufactured by Nitto Seiko Analytech Co., Ltd., with the Ar gas flow rate set at 200 mL/min and the O ₂ gas flow rate set at 400 mL/min, and the heater inlet temperature Complete combustion was carried out at 900°C and outlet temperature at 1000°C. The flow rate of the eluent was 1.5 mL/min, and the column temperature was 35°C. After the gas generated during combustion of the powder was absorbed by the absorption liquid, 20 μL of the absorption liquid was introduced into an ion chromatograph to obtain a chromatogram using an electrical conductivity detector. The peak area of the obtained chromatogram was determined, and the chlorine content was calculated using the calibration curve method.

As the eluent, sodium carbonate and sodium hydrogen carbonate were added to ultrapure water and stirred well to create an aqueous solution containing 286 mg/kg of sodium carbonate and 25 mg/kg of sodium hydrogen carbonate, which was used. The absorption liquid was prepared by adding dipotassium hydrogen phosphate and a hydrogen peroxide solution to ultrapure water and stirring well to prepare an aqueous solution containing 25 mg/kg of phosphorus and 0.3 mL/L of hydrogen peroxide. In addition, as for the reagent specification, if there was a chromatography specification, a chromatography specification was used, and if there was not, a first-class reagent was used.

[Oil absorption amount of boiled linseed]
5.0 g of magnesium titanium double oxide powder was heaped on a glass plate. One drop of boiled linseed oil, which had been previously held in a microburette, was dropped into the center of the sample, and the entire sample was kneaded uniformly with a spatula. Similarly, the operation of adding one or two drops of oil to the boiled linseed and kneading was repeated, and the operation was completed when the entire sample became a hard uniform putty-like mass. When the amount of boiled linseed oil used is x mL, the oil absorption amount a (mL/100 g) is expressed by the following formula.
a=100・x/5.0

[Average primary particle diameter]
Measurement was performed using a transmission electron microscope JEM-1400plus manufactured by JEOL Ltd. The observation magnification was 5,000 times, and if the particle size was small and it was difficult to measure the particle size, it was enlarged to 2 times during printing as necessary. The projected area circular equivalent diameters of 100 or more primary particles were measured from the projected image, taking into account the magnification of enlargement, and the average value was calculated, which was defined as the average primary particle diameter in the present invention.

[Median diameter]
The particle size distribution was measured using a particle size distribution measuring device Microtrac (registered trademark) MT3300EX II, which is a laser light diffraction scattering particle size analyzer manufactured by Microtrac Bell. Pure water was used as the dispersion medium. After dropping an appropriate amount of the magnesium titanium double oxide powder into an ultrasonic dispersion tank of an automatic sample circulation machine attached to the measuring device, ultrasonic dispersion was performed at an output of 40 W for 180 seconds. After this, each measurement parameter was set to 1.33 for the refractive index of ion-exchanged water, 1.33 for the light transmittance of the particles to be measured, 60 seconds for measurement time, and a particle size corresponding to 50% of the volume standard in the integrated particle size distribution. was taken as the median diameter.

[Titanium dioxide peak and crystallite diameter]
X-ray diffraction measurements were performed using a powder method using an X-ray diffraction device RINT-TTR III manufactured by Rigaku Corporation. Magnesium titanium double oxide powder was ground in a mortar and packed into a cell at about 1.5 g ± 0.2 g, with a starting angle of 10.0000°, an ending angle of 75.0000°, and a sampling width of 0.0200°. , the scanning speed is 4.0000°/min, the divergence slit is 0.5°, the scattering slit is 0.5°, the width of the receiving slit is 0.15mm, the characteristic X-ray uses copper for the cathode, and the wavelength is 0. The wavelength was set to 15418 nm. The obtained X-ray diffraction pattern was subjected to background processing using powder X-ray analysis software PDXL2 manufactured by Rigaku Co., Ltd., and smoothing and peak detection were performed. The peak intensity of titanium dioxide appearing between 25.00° and 28.00° was calculated. When the obtained X-ray diffraction pattern is printed on a full A4 page, the peak of titanium dioxide cannot be visually confirmed, or the peak intensity of titanium dioxide is 2.0 when the peak intensity of the (104) plane is taken as 100. When it is less than 100%, it cannot be distinguished from the noise of the device used for measurement, so it is assumed that the peak of titanium dioxide does not exist (not observed). If there is no titanium dioxide peak, it can be determined that the magnesium titanium double oxide powder does not contain titanium dioxide in an amount that could affect its properties. If a peak was present, the peak intensity of titanium dioxide was calculated when the peak intensity of the (104) plane was set as 100.

In addition, the crystallite diameter in the (104) plane of magnesium titanate MgTiO ₃ that appeared in the range of 32.00° to 33.50° with a diffraction angle 2θ was calculated, and this was calculated as the crystallite diameter of the magnesium titanium double oxide powder. The diameter was taken as the diameter.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to examples, but the following examples are merely shown for illustrative purposes, and the scope of the invention is not limited thereto in any way.
In addition, in the stirring operations described in the Examples and Comparative Examples, properties related to the behavior of the liquid during stirring, such as the amount of liquid, viscosity of the liquid, and the shape of the container, are taken into consideration to ensure that the entire liquid is mixed uniformly and The rotation speed is adjusted appropriately to prevent droplets from scattering around. In addition, in cases where the same effect can be obtained no matter which company's product is used, such as hydrochloric acid, the name of the manufacturer and distributor is omitted.

[Example 1]
After deiron bleaching the metatitanic acid obtained by the sulfuric acid method, aqueous sodium hydroxide solution was added to adjust the pH to 9.0, followed by desulfurization treatment, followed by adding hydrochloric acid to neutralize to pH 5.8, filtering and washing with water. A metatitanic acid cake having a sulfur content of 9.3 g/kg in terms of SO ₃ was obtained. Water was added to the washed cake to make a slurry with a Ti content of 2.13 mol/L, and then hydrochloric acid was added to adjust the pH to 1.4 to perform peptization. 857.4 mol of the obtained metatitanic acid slurry was collected as TiO ₂ and 1028.8 mol of magnesium hydroxide #200 manufactured by Kamishima Chemical Industry Co., Ltd. was added thereto, and the first adjusted pH of the mixed slurry was 12.0. After adding an aqueous sodium hydroxide solution to the mixture, the mixture was stirred and mixed for 2.5 hours.

To the obtained mixed slurry, 25.7 g of Himolock (registered trademark) SS-120 manufactured by Heimo Co., Ltd. and 25.7 g of Himolock (registered trademark) MP-173H manufactured by Heimo Co., Ltd. were simultaneously added as flocculants, and then filter press was applied. The first water washing was carried out using. At this time, forward washing was performed until the electrical conductivity of the filtrate became 300 μS/cm or less, and then, switching to back washing was performed, and water washing was performed again until the electrical conductivity of the filtrate became 300 μS/cm or less. After that, washing with water was stopped and the mixture was filtered.

The obtained solid content was dried in a dryer at 130°C for 20 hours. The dried solid content was sized with a screen diameter of 4 mm using a Power Mill P-3 model manufactured by Dalton Co., Ltd., and calcined at 900° C. for 6 hours in an air atmosphere. The fired product was coarsely pulverized using a roller compactor WP105x40 manufactured by Freund Turbo Industries Co., Ltd., and then crushed with a mesh diameter of 2 mm using a micropulperizer AP-1 (hereinafter referred to as "micropulperizer") manufactured by Hosokawa Micron Corporation. Shattered. Next, it was washed in a solution prepared by adding hydrochloric acid to pure water. After the completion of the reaction, hydrochloric acid was added to adjust the second adjusted pH to 5.0. Furthermore, in the second water washing, forward washing was performed until the electrical conductivity of the filtrate became 100 μS/cm or less, and then, switching to back washing was performed, and water washing was performed again until the electrical conductivity of the filtrate became 100 μS/cm or less. Solid-liquid separation was performed and dried at 120° C. in the atmosphere to obtain magnesium titanium double oxide powder. The amount of sodium eluted per 1.0 kg of the obtained powder was 3 mg, the amount of chlorine eluted was 2 mg, and the average primary particle diameter was 410 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 896 mg, the chlorine content is 5 mg, the eluted sodium is 3 mmol/mol of the content, the boiled linseed oil absorption is 18 mL/100 g, the median diameter is 0.6 μm, and the crystal The particle diameter was 98 nm.

[Example 2]
Magnesium titanium double oxide powder was obtained in the same manner as in Example 1 except that the firing temperature was 1150°C. The amount of sodium eluted per 1.0 kg of the obtained powder was 5 mg, the amount of chlorine eluted was 2 mg, and the average primary particle diameter was 1230 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 404 mg, the chlorine content is 6 mg, the eluted sodium is 12 mmol/mol of the content, the boiled linseed oil absorption is 14 mL/100 g, the median diameter is 2.6 μm, and the crystal The particle diameter was 128 nm.

[Example 3]
In the first water washing, after starting normal washing, switch to back washing when the electrical conductivity of the filtrate becomes 4000 μS/cm or less, switch again to normal washing when it becomes 1000 μS/cm or less, and then switch to normal washing at 700 μS/cm or less. When the electrical conductivity became less than 300 μS/cm, backwashing was performed again, and after 500 μS/cm, the cleaning method was changed every time the electrical conductivity changed by 100 μS/cm, and when the electrical conductivity became less than 300 μS/cm, water washing was completed and the firing temperature Magnesium titanium double oxide powder was obtained in the same manner as in Example 1 except that the temperature was 1000°C. The amount of sodium eluted per 1.0 kg of the obtained powder was 48 mg, the amount of chlorine eluted was 29 mg, and the average primary particle diameter was 1320 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 631 mg, the chlorine content is 30 mg, the eluted sodium is 76 mmol/mol of the content, the boiled linseed oil absorption is 18 mL/100 g, the median diameter is 3.8 μm, and the crystal The particle diameter was 117 nm.

[Example 4]
Magnesium titanium double oxide powder was obtained in the same manner as in Example 1 except that the firing temperature was 1000°C. The amount of sodium eluted per 1.0 kg of the obtained powder was 4 mg, the amount of chlorine eluted was 4 mg, and the average primary particle diameter was 790 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 330 mg, the chlorine content is 5 mg, the eluted sodium is 12 mmol/mol of the content, the boiled linseed oil absorption is 14 mL/100 g, the median diameter is 1.1 μm, and the crystal The particle diameter was 113 nm.

[Example 5]
Magnesium titanium double oxide powder was obtained in the same manner as in Example 1, except that the first adjusted pH of the mixed slurry was 11.0 and the firing temperature was 1050°C. The amount of sodium eluted per 1.0 kg of the obtained powder was 6 mg, the amount of chlorine eluted was 5 mg, and the average primary particle diameter was 770 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 261 mg, the chlorine content is 5 mg, the eluted sodium is 23 mmol/mol of the content, the boiled linseed oil absorption is 18 mL/100 g, the median diameter is 1.1 μm, and the crystal The particle diameter was 103 nm.

[Example 6]
Magnesium titanium double oxide powder was obtained in the same manner as in Example 5, except that the first adjusted pH of the mixed slurry was adjusted to 10.0. The amount of sodium eluted per 1.0 kg of the obtained powder was 6 mg, the amount of chlorine eluted was 6 mg, and the average primary particle diameter was 700 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 221 mg, the chlorine content is 6 mg, the eluted sodium is 27 mmol/mol of the content, the boiled linseed oil absorption is 17 mL/100 g, the median diameter is 1.1 μm, and the crystal The particle diameter was 100 nm.

[Example 7]
Magnesium titanium double oxide was washed in the same manner as in Example 3, except that the first washing was performed by the decantation method until the electrical conductivity of the supernatant liquid became 300 μS/cm or less, and only filtration was performed using a filter press. A powder was obtained. The amount of sodium eluted per 1.0 kg of the obtained powder was 14 mg, the amount of chlorine eluted was 6 mg, and the average primary particle diameter was 780 nm, and no titanium dioxide peak was detected in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 451 mg, the chlorine content is 12 mg, the eluted sodium is 31 mmol/mol of the content, the boiled linseed oil absorption is 14 mL/100 g, the median diameter is 1.1 μm, and the crystal The particle diameter was 102 nm.

[Example 8]
3.76 mol of surface-untreated titanium dioxide powder with an average primary particle diameter of 0.18 μm and 5.26 mol of magnesium hydroxide were repulped into pure water, dispersed in a wet bead mill, and the first adjusted pH of the dispersion slurry was adjusted. An aqueous sodium hydroxide solution was added so that the temperature was 13.0. The obtained slurry was washed with water for the first time after adding a flocculant in the same manner as in Example 1, and the solid content after washing was dried in a dryer at 150° C. for 20 hours. The dried solid content was calcined at 950° C. for 0.8 h in an air atmosphere. The obtained baked product was washed in a solution prepared by adding hydrochloric acid to pure water to adjust the second adjusted pH to 5.0, and then a second water washing was performed in the same manner as in Example 1. Thereafter, it was dried in the air at 120° C. for 12 hours to obtain a magnesium titanium double oxide powder. The amount of sodium eluted per 1.0 kg of the obtained powder was 9 mg, the amount of chlorine eluted was 4 mg, and the average primary particle diameter was 320 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 171 mg, the chlorine content is 7 mg, the eluted sodium is 53 mmol/mol of the content, the boiled linseed oil absorption is 42 mL/100 g, the median diameter is 0.6 μm, and the crystal The particle diameter was 61 nm.

[Example 9]
The magnesium titanium double oxide powder obtained in Example 4 was pulverized with a screen diameter of 2 mm using a micro pulperizer, and XIAMETER, manufactured by Dow Toray Industries, Inc., which is 3-glycidoxypropyltrimethoxysilane, was used as a surface treatment agent. (Registered Trademark) OFS-6040 Silane was added at 5 g/kg to the powder, mixed for 8 minutes at a circumferential speed of 8 m/s using a mixer FM-10B manufactured by Mitsui Miike Kakoki Co., Ltd., and then heat-treated at 90° C. for 4 hours. The heat-treated product was pulverized using a micropulperizer with a screen diameter of 0.5 mm. The amount of sodium eluted per 1.0 kg of the obtained powder was 5 mg, the amount of chlorine eluted was 2 mg, and the average primary particle diameter was 790 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 262 mg, the chlorine content is 5 mg, the eluted sodium is 19 mmol/mol of the content, the boiled linseed oil absorption is 17 mL/100 g, the median diameter is 1.2 μm, and the crystal The particle diameter was 113 nm.

[Example 10]
Magnesium titanium double oxidation was performed in the same manner as in Example 9, except that 4 g/kg of Dynasylan (registered trademark) AMEO, manufactured by Evonik Japan Co., Ltd., which is 3-aminopropyltriethoxysilane, was used as a surface treatment agent for the powder. A powder was obtained. The amount of sodium eluted per 1.0 kg of the obtained powder was 2 mg, the amount of chlorine eluted was 3 mg, and the average primary particle diameter was 790 nm, and no titanium dioxide peak was detected in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 337 mg, the chlorine content is 5 mg, the eluted sodium is 6 mmol/mol of the content, the boiled linseed oil absorption is 14 mL/100 g, the median diameter is 1.2 μm, and the crystal The particle diameter was 113 nm.

[Comparative example 1]
8.6 mol of TiO ₂ was collected from the metatitanic acid slurry obtained in the same manner as in Example 1, and after adding 10.3 mol of magnesium hydroxide thereto, the first adjusted pH of the mixed slurry was adjusted to 13.0. Aqueous sodium hydroxide solution was added. Thereafter, the mixture was stirred and mixed for 2.5 hours. After simultaneously adding 0.3 g of Himolock (registered trademark) SS-120 manufactured by Heimo Co., Ltd. and 0.3 g of Himolock (registered trademark) MP-173H manufactured by Heimo Co., Ltd. as a flocculant, forward washing was started in the first water washing. When the electrical conductivity of the filtrate became 500 μS/cm or less, the process was switched to backwashing, and when it became 500 μS/cm or less again, the backwashing was completed. Thereafter, it was filtered, and the solid content after washing with water was dried in a dryer at 120° C. for 20 hours. The dried solid content was calcined at 1000° C. for 6 hours in an air atmosphere.

The obtained fired product was pulverized and then washed in a solution prepared by adding hydrochloric acid to pure water, and then the second adjusted pH was adjusted to 5.0. The subsequent second washing was also carried out in the same manner as the first washing. It was dried in the air at 120°C to obtain a magnesium titanium double oxide powder. The amount of sodium eluted in 1.0 kg of the obtained powder was 159 mg, the amount of chlorine eluted was 3 mg, and the average primary particle diameter was 820 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 3870 mg, the chlorine content is 6 mg, the eluted sodium is 41 mmol/mol of the content, the boiled linseed oil absorption is 11 mL/100 g, the median diameter is 1.5 μm, and the crystal The particle diameter was 106 nm.

[Comparative example 2]
Magnesium titanium double oxide powder was obtained in the same manner as in Comparative Example 1, except that only the second water washing was carried out in the same manner as in Example 1. The amount of sodium eluted per 1.0 kg of the obtained powder was 134 mg, the amount of chlorine eluted was 3 mg, and the average primary particle diameter was 810 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 1520 mg, the chlorine content is 5 mg, the eluted sodium content is 88 mmol/mol, the boiled linseed oil absorption is 12 mL/100 g, the median diameter is 1.1 μm, and the crystal The particle diameter was 101 nm.

[Comparative example 3]
Magnesium titanium double oxide powder was obtained in the same manner as in Example 1, except that the firing temperature was 1000° C. and the sample was lightly rinsed with water and dried without performing the second water washing. Note that the electrical conductivity of the water used for light rinsing was 19,000 μS/cm. The amount of sodium eluted per 1.0 kg of the obtained powder was 10 mg, the amount of chlorine eluted was 170 mg, and the average primary particle diameter was 810 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 383 mg, the chlorine content is 173 mg, the eluted sodium is 26 mmol/mol of the content, the boiled linseed oil absorption is 13 mL/100 g, the median diameter is 1.2 μm, and the crystal The particle diameter was 113 nm.

[Comparative example 4]
3.76 mol of surface-untreated titanium dioxide powder whose primary particle average diameter is 0.18 μm and 5.26 mol of magnesium carbonate were dry mixed for 2 hours in a vibration mill AH-1 manufactured by Tsukishima Machine Sales Co., Ltd. The mixed powder was fired as it was at 950° C. for 0.8 h in an air atmosphere. The operations after taking out the fired product were carried out in the same manner as in Example 1 to obtain a magnesium titanium double oxide powder. The amount of sodium eluted per 1.0 kg of the obtained powder was 1 mg, the amount of chlorine eluted was below the detection limit, and the average primary particle diameter was 250 nm, and no titanium dioxide peak was observed in X-ray diffraction measurement. The sodium content per 1.0 kg of powder is 144 mg, the chlorine content is 3 mg, the eluted sodium is 7 mmol/mol of the content, the boiled linseed oil absorption is 43 mL/100 g, the median diameter is 0.6 μm, The crystallite diameter was 61 nm.

[Comparative example 5]
After adding magnesium hydroxide, magnesium titanium double oxide powder was prepared in the same manner as in Example 1, except that the first water washing was performed without adding any sodium hydroxide aqueous solution and the firing temperature was 1000°C. I got it. Note that the pH after adding magnesium hydroxide was 9.4. The amount of sodium eluted per 1.0 kg of the obtained powder was 2 mg, the amount of chlorine eluted was 2 mg, and the average primary particle diameter was 770 nm. In the X-ray diffraction measurement, a peak of titanium dioxide was observed, and the intensity was 25.9 when the peak intensity of the (104) plane was taken as 100. The sodium content per 1.0 kg of powder is 205 mg, the chlorine content is 6 mg, the eluted sodium is 10 mmol/mol of the content, the boiled linseed oil absorption is 18 mL/100 g, the median diameter is 1.0 μm, and the crystal The particle diameter was 101 nm.

Table 1 shows the manufacturing conditions of the magnesium titanium double oxide powders of Examples and Comparative Examples, and Table 2 shows the characteristics of the magnesium titanium double oxide powders obtained in Examples and Comparative Examples.

As shown in Table 2, after wet mixing, alkali is added, and before firing, the liquid part is washed with water until the electrical conductivity becomes 300 μS/cm or less (first water washing), and then washed with acid after baking. After that, by washing with water until the electrical conductivity of the liquid part becomes 100 μS/cm or less (second water washing), the amount of sodium eluted per 1.0 kg of powder is 100 mg or less, and the amount of chlorine eluted is 50 mg or less, A magnesium titanium double oxide powder was obtained in which the average primary particle diameter of the sample was 300 nm or more and 5000 nm or less, and in which no titanium dioxide peak was observed. In the present invention, magnesium titanium double oxide has a small elution amount of sodium and chlorine in both cases where a coating layer is not formed on the surface (Examples 1 to 8) and when a coating layer is formed (Examples 9 and 10). I was able to obtain a powder. On the other hand, when at least one of the first water washing and the second water washing did not satisfy the above conditions, the amount of sodium elution and/or the amount of chlorine elution exceeded the desired range. For the dry mixed product (Comparative Example 4) and the sample in which no alkali was added after wet mixing (Comparative Example 5), the elution amount was within the range, but in terms of average primary particle size and residual unreacted materials, Couldn't solve the problem.

Furthermore, a technically important point in the magnesium titanium double oxide powder of the present invention is that even if the sodium content fluctuates, the amount of elution can be kept constant. For example, although the magnesium titanium double oxide powder obtained in Example 1 described in the specification contains slightly more than five times as much sodium as the magnesium titanium double oxide powder obtained in Example 8, There is no significant difference in the amount of sodium eluted compared to the magnesium titanium double oxide powder obtained in Example 8. It has been revealed that the present invention enables an approach of reducing only the amount of sodium eluted without significantly changing the sodium content in the powder. By applying the production method of the present invention, manufacturers can reduce the amount of sodium eluted from magnesium titanium double oxide powder while maintaining the proven raw material composition and raw material blending ratio.

The knowledge about the amount of sodium eluted according to the present invention can also be applied to reducing the amount of other impurities eluted.
As described above, according to the present invention, it is possible to obtain a magnesium titanium double oxide powder with a small amount of sodium elution and a small amount of chlorine elution. When the magnesium titanium double oxide powder of the present invention is used as an inorganic filler in a resin encapsulant for semiconductors, it can adjust the dielectric constant of the high dielectric constant resin encapsulant for semiconductors to a desired value, and It is possible to prevent corrosion of the metal of the wiring, has excellent usability, and has stable characteristics because it does not contain unreacted substances.

Claims

Sodium in the powder that has an average primary particle diameter of 300 nm or more and 5000 nm or less as observed by transmission electron microscopy, and that dissolves into water when the powder is immersed in water at a concentration of 100 g/L and held at 95°C for 20 hours. The amount of chlorine is 100 mg or less per 1.0 kg of powder, the amount of chlorine is 50 mg or less per 1.0 kg of powder,
A magnesium titanium double oxide powder in which no titanium dioxide peak is observed in X-ray diffraction.
The magnesium titanium double oxide powder according to claim 1, wherein the sodium content per 1.0 kg of powder is 1000 mg or less, and the chlorine content per 1.0 kg of powder is 50 mg or less.
The magnesium titanium double oxide powder according to claim 1 or 2, wherein of the sodium contained, the amount of sodium eluted in water is 85 mmol/mol or less.
The magnesium titanium double oxide powder according to claim 1 or 2, wherein the boiled linseed oil absorption amount is 14 mL/100 g or more and 45 mL/100 g or less.
The magnesium titanium double oxide powder according to claim 1 or 2, which has a median diameter of 0.5 μm or more and 10.0 μm or less as measured by laser scattering diffraction particle size analysis.
Claim 1 or 2, wherein the crystallite diameter in the (104) plane of MgTiO 3 that appears in the range of diffraction angle 2θ of 32.00° or more and 33.50° or less in X-ray diffraction is in the range of 60 nm or more and 130 nm or less. Magnesium titanium double oxide powder as described.
The method for producing a magnesium titanium double oxide powder according to claim 1 or 2, comprising the following steps A to E.
A: A step of mixing a titanium source and a magnesium source in a wet state, adding an alkali, and adjusting the pH to a range of 9.5 or more and 13.0 or less to obtain a slurry,
B: washing the slurry obtained in step A with water until the electrical conductivity of the liquid part becomes 300 μS/cm or less, and performing solid-liquid separation to obtain a mixture of a titanium source and a magnesium source;
C: a step of firing the mixture obtained in step B and reacting the titanium source and the magnesium source to obtain a fired product;
D: A step of washing the baked product obtained in step C with an acid and adjusting the pH to a range of 4.0 to 7.0 to obtain a slurry;
E: washing the slurry obtained in step D with water until the electrical conductivity of the liquid part becomes 100 μS/cm or less, and performing solid-liquid separation to obtain a solid content;
F: Step of drying the solid content obtained in Step E.
The method for producing magnesium titanium double oxide powder according to claim 7, wherein the alkali added in the step A is a sodium compound and/or a potassium compound.
The method for producing a magnesium titanium double oxide powder according to claim 7 or 8, further comprising the step of applying an inorganic or organic coating layer to at least a part of the surface of the particles constituting the powder.
The magnesium titanium double oxide powder according to claim 1 or 2, which has an inorganic or organic coating layer on the powder surface.
An inorganic filler used in a resin encapsulant for semiconductors, comprising the magnesium titanium double oxide powder according to claim 1 or 2.